In a modern supermarket or drugstore, the individual items packaged in cans, cartons or other containers are hand stamped to show the selling price. Because hundreds or thousands of such items must be marked, the operation becomes a tedious daily routine for the people who stock the shelves, and the speed and efficiency with which it can be accomplished is an important economic consideration. For these reasons, even the slightest improvement in the device is worthwhile if it contributes to the speed of the operation or to the reduction of operator fatigue.